The present invention relates to non-steroidal compounds which can bind to steroid receptors, and more particularly to compounds that can bind to both a steroid receptor and a radionuclide for either diagnostic or therapeutic purposes.
Steroids are produced by many human tissues and exert significant impacts on the health and activity of humans. For example, progesterone is secreted from the corpus Iuteum, and in concert with estradiol, acts to maintain the uterine endometrium for egg implantation in females. Testosterone, another so-called sex hormone, is secreted by Leydig cells of testis, and after bioconversion to dihydrotestosterone, effects production of sperm proteins in Sertoli cells and is central to the development of secondary sex characteristics in males. Aldosterone, secreted from glomerulosa cells of the adrenal cortex, causes sodium ion uptake via conductance channels and thereby raises blood pressure and fluid volume during periods of stress.
After secretion, steroids are transported through the blood to receptor sites. Typically, steroids are bound to a protein during transport. Corticosteroid binding globulin protein, sex hormone binding protein, androgen binding protein and albumin are the most common binding proteins. Regardless of their bound form, steroids become unbound near their target cells and then enter the target cells to bind with a receptor. Depending on the cell, steroid receptors appear to be located within either the cell""s cytoplasm or nucleus, and possibly at both locations. In structural terms, the receptor is a protein which, upon binding to a steroid, undergoes a change in conformation and activity. For instance, a steroid may induce a receptor protein to bind to a specific region of DNA, where that region then becomes accessible to RNA polymerase with subsequent stimulation of transcription.
The foregoing brief summary of steroids and steroid receptors serves to illustrate the importance of this biological system to humans and, in fact, to most animals. Further discussion of steroids and their action can be found in many texts including, to name a few, Gower, D. B. Steroid Hormones Croom Helm Biology in Medicine Series, Year Book Medical Publishers, Chicago, Ill. (1979); Peters, H. et al. The Ovary University of California Press, Berkeley, Calif. (1980); Hadley, M. C. Endocrinology Prentice-Hall, Inc., Englewood Cliffs, N.J. (1984); Norman, A. W. et al. Hormones Academic Press, Inc. New York, N.Y. (1987); Zeelen, F. J. Pharmacochemistiy Library, 15: Medicinal Chemistry of Steroids Elsevier, Amsterdam, Netherlands (1990); Bohl, M. et al. Molecular Structure and Biological Activity of Steroids, CRC Press, Boca Raton, Fla. (1992); and Parker, M. G. Steroid Hormone Action IRL Oxford, United Kingdom (1993).
Knowledge about the location and activity of steroid receptors is generally important to understanding the biochemistry of life and disease. Research is pressing forward to supplement current knowledge, which may be applied to diagnostic as well as therapeutic procedures. Diagnostic techniques which afford quantitative information about the population of receptor sites in a tissue are particularly useful in monitoring health of the tissue. Relevant to therapeutic procedures, one goal of medicinal chemists is to provide caregivers with tools to modulate the activity of steroid receptors.
One general approach to identifying biological receptors, whether for steroids or any of a host of other biologically important molecules, has been to design chemicals which may be termed xe2x80x9creceptor analogsxe2x80x9d that both bind to a receptor and carry with them a xe2x80x9cfunctional agentxe2x80x9d. For diagnostic purposes, the functional agent may be a xe2x80x9cmarkerxe2x80x9d, which is an atom or molecular fragment that can be visualized or otherwise detected in some way. For example, the marker may be a radionuclide that emits a radioactive species which can be detected by a molecular nuclear medical technique such as scintigraphic imaging. This approach allows a technician to administer a receptor analog to a subject and, after waiting an appropriate time for binding to occur, make an image of the subject which shows the location(s) where binding has occurred. In some instances, the intensity of the image may be used to develop a quantitative understanding of receptor activity. For example, cancerous cells tend to have a higher density of receptor sites than non-cancerous cells of the same type, due to an increased expression of the receptor gene. Thus, identification of a high density of steroid receptor sites may provide some indication of cancer.
Receptor analogs may be used in therapeutic as well as diagnostic applications. For instance, the functional agent of the receptor analog may be, or can be made toxic to surrounding tissue. Upon administration to a subject, the therapeutic receptor analog will bind to receptors in or on targeted cell types, and if those cell types are cancerous, then the cancer cells may be killed. For instance, the receptor analog may have a structure similar to a steroid, and thus bind to steroid receptors, however the analog has a functional agent that is a radionuclide which is toxic to nearby cells.
The approach of using steroid receptor analogs for diagnostic and therapeutic purposes has been described. However, to date, known steroid receptor analogs have not provided the desired degree of receptor binding properties, including specificity for specific receptor binding sites and strength of binding. See, e.g., Hom R. K. et al. Nucl. Med. and Biology 24:485-498 1997; Hom R. K. et al. Presentation from XIIth International Symposium on Radiopharmaceutical Chemistry, Uppsala, Sweden, Jun. 15-19, 1997, pp. 510-511. Hom R. K. et al. J. Org. Chem. 62:6290-6297, 1997; Labaree, D. C. J Nucl. Med. 38(3):402-409 March 1997; Avril, N. et al. J Nucl. Med. 38(8):1186-1191 August 1997; Top, S. et al. U.S. Pat. No. 5,554,602, issued Sep. 10, 1996; Bonasera, T. A. et al. J. Nucl. Med. 37(6):1009-1015 June 1996; Katzenellenbogen, J. J. Nucl. Med. 36(6, Supp):8S-13S June, 1995; Choe, Y. S. et al. J. Nucl. Med. 36(65, Proceedings):39P, May, 1995; O""Neil, J. P. et al. Bioconjugate Chem. 5:182-193 1994; Chi, D. Y. et al. J. Med. Chem. 37:928-937 1994; Chi, D. Y. et al. J.A.C.S. 115:7045-7046 1993; DiZio, J. P. et al. J. Nucl. Med. 33(4):558-569 April 1992; and DiZio, J. P. et al. Bioconjugate Chem. 2:353-366 1991.
Therefore, there is a need in the art for effective receptor analogs, which demonstrate specificity to an intended steroid receptor, and can deliver functional agents to the steroid receptor. The present invention fulfills this need and further provides other related advantages as disclosed herein.
A compound of the formula (I) 
wherein,
A) R1 and R2 together are a steroid receptor binding group where,
i) R1 and R2 are independently selected from 
xe2x80x83where A1, A2, A3, A4, A7 and A8 are independently selected from xe2x80x94CHxe2x80x94, xe2x80x94CXxe2x80x94, xe2x80x94C(OH)xe2x80x94 AND N, where X is halide, with the proviso that not more than three of A1, A2, A3 and A4 are simultaneously N, and not more than one of A7 and A8 are simultaneously N;
A5 and p are independently selected from (A5/p): O/1, S/1, Se/1, C(xe2x95x90O)O/1, N/2, P/2, and Si/3, where R3 at each occurrence is independently selected from H, C1-C10hydrocarbyl, and a protecting group for A5, or A5xe2x80x94(R3)p may together form xe2x80x94NO2, hydrogen or halogen;
A6 is selected from S, O and NH;
R4 is selected from H, xe2x80x94OH, halide and C1-C3alkyl;
R5 is selected from H, xe2x80x94OH, halide and C1-C3alkyl; and
R6 is selected from H, xe2x80x94OH, xe2x80x94SH, halide, C1-C3alkyl, C(xe2x95x90O)CH3, thio and oxo;
B) C1 and C2 are joined together by
i) a double bond, or
ii) a single bond, where
a. the single bond may form part of a 3- to 5-membered carbocyclic or heterocyclic ring, the heterocyclic ring containing one heteroatom selected from oxygen, nitrogen and sulfur; or
b. C1 and C2 are independently substituted with H, halogen, or C1-C3alkyl; or
c. C1 may join B1 through a C1xe2x95x90N double bond, and/or C2 may join B2 through a C2xe2x95x90N double bond;
C) 
xe2x80x83represents a number xe2x80x9cnxe2x80x9d of methylene (CH2) or fluoromethylene (CFH or CF2) groups, where n is independently selected at each occurrence from 0, 1 and 2;
D) at least one of B1 and B2 is a metal species binding group, where
i) B1 and B2 may together be capable of binding one metal species and each has a structure selected from 
iii) B1 and B2 may each be capable of binding one metal species and each has a structure independently selected from 
iv) only one of B1 and B2 is capable of binding a metal species, where one of B1 and B2 has a structure selected from D) iii) above, and the other of B1, and B2 is selected from H and groups that affect the in vivo pharmacological behavior of the compound, such as C1-C10hydrocarbyl or a polar group which increases the hydrophilicity of the compound, such as carboxylates, sulfonates and secondary alcohols;
xe2x80x83where,
a. A9 is an electron-donating moiety independently selected at each occurrence from O, S, C(xe2x95x90O)NH and N(R12), where R12 is selected from hydrogen and pro-drug substituents selected from the group consisting of C1-C3alkyl, xe2x80x94C(xe2x95x90O)(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)CH(NH2)(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-OC(xe2x95x90O)xe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94(C1-C3alkylene)-NHC(xe2x95x90O)xe2x80x94Ar, xe2x80x94(C1-C3alkylene)-CN, xe2x80x94(C1-C3alkylene)-NO2, and 
b. R7 and R10 each have a structure which at each occurrence is independently selected from 
xe2x80x83where R13 and R14 are independently selected from H, R15, xe2x80x94CN, xe2x80x94NO2, xe2x80x94NO, xe2x80x94C(OC1-C3alkyl)xe2x95x90NH, xe2x80x94Nxe2x95x90Cxe2x95x90O, xe2x80x94Nxe2x95x90Cxe2x95x90S, and xe2x80x94C(xe2x95x90O)OR15 where R15 is C1-C6hydrocarbyl, such that when R10 is bonded to E, then R13 is a direct bond to E;
c. R8, R9 and R11 are independently selected from H and protecting groups for the A9 or A10 moiety to which the R8, R9 or R11 is bonded;
d. A9 and R11 may together form xe2x80x94N(CH2xe2x80x94COOH)2;
e. A10 is independently selected from O and S; and
f. E is an xe2x80x9cextender armxe2x80x9d which covalently links a metal species binding site to C1 or C2, and has a structure which provides a stable chain of 2-60 atoms selected from carbon, oxygen, nitrogen and sulfur.
In another embodiment, the present invention provides compounds of the formula (I) 
wherein,
A) R1 and R2 together are a steroid receptor binding group where,
i) R1 and R2 are independently selected from 
xe2x80x83where A1, A2, A3, A4, A7 and A8 are independently selected from xe2x80x94CHxe2x80x94, xe2x80x94CXxe2x80x94, xe2x80x94C(OH)xe2x80x94 and N, where X is halide, with the proviso that not more than three of A1, A2, A3 and A4 are simultaneously N, and not more than one of A7 and A8 are simultaneously N;
A5 and p are independently selected from (A5/p): O/1, S/1, Se/1, C(xe2x95x90O)O/1, N/2, P/2, and Si/3, where R3 at each occurrence is independently selected from H, C1-C10hydrocarbyl, and a protecting group for A5, or A5xe2x80x94(R3)p may together form xe2x80x94NO2, hydrogen or halogen;
A6 is selected from S, O and NH;
R4 is selected from H, xe2x80x94OH, halide and C1-C3alkyl;
R5 is selected from H, xe2x80x94OH, halide and C1-C3alkyl; and
R6 is selected from H, xe2x80x94OH, xe2x80x94SH, halide, C1-C3alkyl, C(xe2x95x90O)CH3, oxo and thio;
B) C1 and C2 are joined together by
i) a double bond, or
ii) a single bond, where
a. the single bond may form part of a 3- to 5-membered carbocyclic or heterocyclic ring, the heterocyclic ring containing one heteroatom selected from oxygen, nitrogen and sulfur; or
b. C1 and C2 are independently substituted with H, halogen, or C1-C3alkyl; or
c. C1 may join B1 through a C1xe2x95x90N double bond, and/or C2 may join B2 through a C2xe2x95x90N double bond;
C) 
xe2x80x83represents a number xe2x80x9cnxe2x80x9d of methylene (CH2) or fluoromethylene (CFH or CF2) groups, where n is independently selected at each occurrence from 0, 1 and 2;
D) at least one of B1 and B2 is a metal species binding group, where
i) B1 and B2 may together be capable of binding one metal species and each has a structure selected from 
ii) B1 and B2 may together form the cyclic structure 
iii) B1 and B2 may each be capable of binding one metal species and each has a structure independently selected from 
iv) only one of B1 and B2 is capable of binding a metal species, where one of B1 and B2 has a structure selected from D) iii) above, and the other of B1 and B2 is selected from H and groups that affect the in vivo pharmacological behavior of the compound, such as C1-C10hydrocarbyl or a polar group which increases the hydrophilicity of the compound, such as carboxylates, sulfonates and secondary alcohols;
xe2x80x83where,
a. A9 is an electron-donating moiety independently selected at each occurrence from O, S, C(xe2x95x90O)NH and N(R12), where R12 is selected from hydrogen and pro-drug substituents selected from the group consisting of C1-C3alkyl, xe2x80x94C(xe2x95x90O)(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)CH(NH2)(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-OC(xe2x95x90O)xe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94(C1-C3alkylene)-NHC(xe2x95x90O)xe2x80x94Ar, xe2x80x94(C1-C3alkylene)-CN, xe2x80x94(C1-C3alkylene)-NO2, and 
b. R7 and R10 each have a structure which at each occurrence is independently selected from 
xe2x80x83where R13 and R14 are independently selected from H, R15, xe2x80x94CN, xe2x80x94NO2, xe2x80x94NO, xe2x80x94C(OC1-C3alkyl)xe2x95x90NH, xe2x80x94Nxe2x95x90Cxe2x95x90O, xe2x80x94Nxe2x95x90Cxe2x95x90S, and xe2x80x94C(xe2x95x90O)OR15 where R15 is C1-C6hydrocarbyl, such that when R10 is bonded to E, then R13 is a direct bond to E;
c. R8, R9 and R11 are independently selected from H and protecting groups for the A9 or A10 moiety to which the R8, R9 or R11 is bonded;
d. A9 and R11 may together form xe2x80x94N(CH2xe2x80x94COOH)2;
e. A10 is independently selected from O and S; and
f. E is an xe2x80x9cextender armxe2x80x9d which covalently links a metal species binding site to C1 or C2, and has a structure which provides a chain of 2-60 atoms selected from carbon, oxygen, nitrogen and sulfur.
In another aspect, the present invention provides a compound of the formula (II) 
wherein, independently at each occurrence,
n is 0 or 1;
the rings surrounded by xe2x80x9cGxe2x80x9d and xe2x80x9cJxe2x80x9d are five- or six-membered rings depending on the value of n, and the rings may be saturated or unsaturated;
A5 and p are independently selected from (A5/p): O/1, S/1, Se/1, C(xe2x95x90O)O/1, N/2, P/2, and Si/3, where R3 at each occurrence is independently selected from H, C1-C10hydrocarbyl, and a protecting group for A5, or A5xe2x80x94(R3)p may together form xe2x80x94NO2, hydrogenxe2x95x90O or halogen;
at least one of B1 and B2 is a metal species binding group, where
i) B1 and B2 may together be capable of binding one metal species and each has a structure selected from 
ii) B1 and B2 may together form the cyclic structure 
iii) B1 and B2 may each be capable of binding one metal species and each has a structure independently selected from 
iv) only one of B1 and B2 is capable of binding a metal species, where one of B1 and B2 has a structure selected from D) iii) above, and the other of B1 and B2 is selected from H and groups that affect the in vivo pharmacological behavior of the compound, such as C1-C10hydrocarbyl or a polar group which increases the hydrophilicity of the compound;
xe2x80x83where,
a. A9 is an electron-donating moiety independently selected at each occurrence from O, S, C(xe2x95x90O)NH and N(R12), where R12 is selected from hydrogen and pro-drug substituents selected from the group consisting of C1-C3alkyl, xe2x80x94C(xe2x95x90O)(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94C(xe2x95x90O)CH(NH2)(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-C(xe2x95x90O)Oxe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-OC(xe2x95x90O)xe2x80x94(H, C1-C3alkyl or Ar), xe2x80x94(C1-C3alkylene)-N(independently H or C1-C3alkyl)2, xe2x80x94(C1-C3alkylene)-NHC(xe2x95x90O)xe2x80x94Ar, xe2x80x94(C1-C3alkylene)-CN, xe2x80x94(C1-C3alkylene)-NO2, and 
b. R7 and R10 each have a structure which at each occurrence is independently selected from 
xe2x80x83where R13 and R14 are independently selected from H, R15, xe2x80x94CN, xe2x80x94NO2, xe2x80x94NO, xe2x80x94C(OC1-C3alkyl)xe2x95x90NH, xe2x80x94Nxe2x95x90Cxe2x95x90O, xe2x80x94Nxe2x95x90Cxe2x95x90S, and xe2x80x94C(xe2x95x90O)OR15 where R15 is C1-C6hydrocarbyl, such that when R10 is bonded to E, then R13 is a direct bond to E;
c. R8, R9 and R11 are independently selected from H and protecting groups for the A9 or A10 moiety to which the R8, R9 or R11 is bonded;
d. A9 and R11 may together form xe2x80x94N(CH2xe2x80x94COOH)2;
e. A10 is independently selected from O and S; and
f. E is an xe2x80x9cextender armxe2x80x9d which covalently links a metal species binding site to the remainder of the molecules, and has a structure which provides a stable chain of 2-60 atoms selected from carbon, oxygen, nitrogen and sulfur.
In another embodiment, the present invention provides chelation products (chelates) of compounds of formulae (I) and (II). The chelation products are compounds of formula (I) and (II) chelated to at least one metal or metal ion (collective a xe2x80x9cmetal speciesxe2x80x9d). Radionuclides are preferred metal species of the present invention. The radionuclide may be in the form of an oxide or nitride, as two examples.
The steroid analogs of the above formulae (I) and (II), and chelates thereof, may be in the form of a solvate or a pharmaceutically acceptable salt, e.g., an acid addition or base addition salt. Such salts include hydrochloride, sulfate, phosphate, citrate, fumarate, methanesulfonate, acetate, tartrate, maleate, lactate, mandelate, salicylate, succinate and other salts known in the art.
A steroid receptor analog, and a chelate thereof, of the present invention may be prepared as a composition by combining it with a pharmaceutically acceptable carrier or diluent. Suitable carriers or diluents include physiological saline. It will be evident to those of ordinary skill in the art that a composition of the present invention may contain more than one steroid receptor analog compound.
In another embodiment, the invention provides a method of binding a steroid analog to a steroid receptor for a therapeutic or diagnostic purpose. The method includes the step of administering to a subject in need thereof a therapeutically or diagnostically effective amount of a steroid receptor analog, chelate thereof, or pharmaceutical composition containing a steroid receptor analog or chelate thereof.
In another embodiment, the present invention provides a method of imaging a steroid receptor. The method includes the step of administering to a subject in need thereof a diagnostically effective amount of a steroid receptor analog, chelate thereof, or pharmaceutical composition containing a steroid receptor analog or chelate thereof.
In another embodiment, the present invention provides a method of killing a cell having a steroid receptor. The method includes the step of administering to a subject in need thereof, in an amount effective to kill a cell, of a steroid receptor analog, chelate thereof, or pharmaceutical composition containing a steroid receptor analog or chelate thereof.